Many refrigeration units, such as household refrigerators, air conditioning units, heat pumps, vending machines for soft drinks, water coolers for drinking water, and other small air conditioning and refrigeration systems use chlorofluorocarbons (CFC's), hydrochlorofluorocarbons CFC's as refrigerants is discussed in detail in U.S. Pat. No. 5,020,331 which is hereby incorporated by reference in its entirety.
It is desirable to avoid open air release of CFC's, which damage the ozone layer of the atmosphere, during transfer of refrigerant to and from such equipment. The reclamation of such refrigerants is both ecologically and economically desirable.
It would be advantageous to have a hand carryable refrigerant recovery unit of limited size and weight having an internal storage tank or container for use in areas where it is not convenient to carry a large recovery unit and separate refrigerant recovery cylinder. Small appliances such as house refrigerators or air conditioning units typically hold refrigerant charges of up to four pounds. Therefore, the internal container must possess sufficient capacity to accommodate the refrigerant charge from at least one small appliance unit. Preferably, the internal container has sufficient capacity to accommodate refrigerant from several refrigerators or other appliances and means for monitoring the level of refrigerant within the container and controlling the flow of refrigerant into the unit when the refrigerant level within the container exceeds a predetermined value.
In addition, it is desirable to have a refrigerant recovery unit which may be connected to a relatively large external tank to allow for evacuation of substantially all of the refrigerant from the internal container and unit and to alternatively allow the refrigerant to be directly stored within the external tank.
In the prior art, there is disclosed a self-contained refrigerant recovery and purification system. The refrigerant withdrawn from a disabled refrigeration unit is initially passed through an oil trap and acid purification filter-drier to remove impurities before the refrigerant gas enters a compressor. The compressed gas is passed through a conduit containing a cutoff valve, a check valve, a purge valve, and a high pressure switch. The gas is converted to a liquid by passage through the condensing coil of a condenser-evaporator. The liquefied refrigerant is then passed through an acid-purification filter-drier and into a receiving tank. The level of refrigerant within the receiving tank is not monitored and no control means is provided to control refrigerant input to the system based upon the level of refrigerant in the tank. The liquefied gas may be discharged to an external holding tank or a portion of the liquefied gas may be used to cool the gas in the condenser coil. The high pressure purge feature allows residual refrigerant in the system to be purged to the atmosphere.
A portable refrigerant recovery and purification system is disclosed in the prior art which consists of an evaporator, a compressor, a condenser, and a refrigerant storage container mounted on a two-wheeled hand truck. Refrigerant is passed through the evaporator, compressed by the compressor, reliquefied at the condenser and fed to a storage container.
One system and method for withdrawing and charging refrigerant from or into a refrigeration system passes withdrawn refrigerant through a vaporizing coil to prevent liquid refrigerant from entering a positive displacement transfer pump. Refrigerant vapor from the pump outlet is liquefied in a cooling coil/heat exchanger, which is, in turn, in communication with a refrigerant disposable storage container.
Another known refrigerant reclamation and charging unit has a compressor and condenser which uses a portion of the refrigerant being evacuated to continuously cool itself. In the reclamation mode, the refrigerant flows in the direction of a standard refrigerant receiver or container by means of a pressure differential created by the cooling.
A refrigerant recovery apparatus is disclosed in the prior art, in which the recovered refrigerant is passed through a filter-dryer acid neutralizer and vapor-liquid separator. The predominantly liquid component is contact-condensed by the cooled refrigerant in the storage reservoir. The predominantly gaseous component is recycled through the compressor and condenser circuit.